 From the "weak" perspective, intergenerational equity would be achieved if losses to the environment that future generations face were offset by gains in economic progress.From the "strong" perspective, no amount of economic progress can justify leaving future generations with a degraded environment.According to Professor Sharon Beder, the "weak" perspective is undermined by a lack of knowledge of the future, as we do not know which intrinsically valuable resources will not be able to be replaced by technology.